Mink growth hormone has been conventionally produced by isolation and purification from the pituitary gland of domesticated minks. Mink growth hormone facilitates the growth of minks by administrating the hormone to them and are very useful physiologically active substances.
Since the mink growth hormone is derived from minks, the production of the mink growth hormone requires many domesticated animals, a long period of time, labor and cost. The present inventors previously provided the growth hormone gene of Dark mink defined by SEQ ID No. 2 in order to produce mink growth hormone by genetic engineering techniques (Japanese Patent Application 315946/1990). However, the Dark mink growth hormone gene was not satisfactory expressed in the transformant.
The present inventors have extensively investigated genes that efficiently expresses the mink growth hormone and successfully found the method.